Offshore radio refers to the practice of radio broadcasting from ships or fixed maritime structures, usually in international waters. The majority of offshore broadcasters have been pirate radio stations, using seaborne broadcasting as a means to circumvent national broadcasting regulations, but the practice has also been used by legitimate broadcasting organisations like the Voice of America.

Offshore pirate stations have operated off the coasts of Belgium, Denmark, Israel, The Netherlands, New Zealand, Sweden, The United Kingdom and even (on rare occasions) The United States. See Pirate radio for full details.